In recent years, the number of touch type input devices, that is, devices adopting a touch panel type has been increased significantly. The number of devices which adopt the touch panel type as an input interface has been increased significantly together with the development of the thinned display technique, such as portable phones, portable game machines, and portable music players as well as bank ATMs and ticket vending machines in stations.
Currently used touch panels are mainly of a resistance film type and an electrostatic capacity type, and in addition to these, there are touch panels using an optical type, an electromagnetic induction type, and elastic surface waves with piezoelectric. Typically, these types are used to detect position information. That is, coordinate information showing in what position on a touch panel the user touches is obtained to execute a designated process based on this information. As typified by bank ATMs, the user touches a button portion displayed on the screen to be able to operate the device as if the user pressed an actual button for operation. With the recent development of the graphic user interface (GUI) process technique, there are also devices in which the user can touch the screen to scroll displayed images or can directly control a graphically displayed slide switch with a finger.
The touch panels have been required to be further varied, so that the request to obtain pressed information together with position information at the same time has been increased recently. That is, if binary information showing in what position on the screen the user touches and how strong the user touches the position is detected, the operability can be further improved.
As a technique in connection with this, Patent Document 1 discloses a technique in which a position detecting device is overlapped with a pressure sensitive sensor to detect position information and pressed information at the same time.
Also, Patent Document 2 discloses a method which uses a piezoelectric film to obtain pressed information and detects in what portion of a plurality of electrode lines formed in a lattice shape on the piezoelectric film a detected voltage appears to obtain position information.    Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 5-61592    Patent Document 2: Japanese Patent Application Laid-Open (JP-A) No. 2006-163618